Natural Factors Calcium Factor+ - 350 mg - Essential for the development and maintenance of healthy bones and teeth, everyone should be sure to maintain adequate levels of this vital mineral - especially women who are prone to osteoporosis. Besides preventing bone loss, Calcium also helps blood clotting, lowers blood pressure and helps activate many enzymes. Natural Factors Calcium Citrate is highly concentrated and soluble, in citrate form, making it easy to absorb and highly bio-available.